Quick take on Fanbase: If VCs are handing out $5 million investments (and the New York Times dishing out plum features) for an idea that is basically the Nth version of "Wikipedia for sports!" I would like to know where I might send my pitch for my own derivative product.
As a consumer, I'm just not seeing how this target of content -- all teams ever! all players ever!-- is being underserved by Wikipedia, the dominant player. And as a potential content producer, Wikipedia offers no barrier to entry to create a page on even the most obscure team or player.
(Few other thoughts: (1) If there is going to be a non-Wikipedia standard in sports information, it will come through ESPN-DB. (2) Allowing users to post YouTube clips is a recipe for the leagues to demand they are taken down, leaving you with non-working links. (3) Ummm: Is there a revenue model?)